Process for treating refractory ores containing precious metals



Patented Mar. 27: 1928.

GEORGE W. B. EVANS,

or wnmamss, VIRGINIA, nssrenon TION COMPANY, OF WASHINGTON, DISTRICT OF COLUMBIA.

. rnocnss ron TREATING rmrnac'romr. onus oon'remmernncrous METALS. I

No Drawing.

My invention relates primarily to the metallurgical art, has special reference to the preliminary treatment of refractory ores for the-recovery of precious metals, such as-gold,

silver, copper and the like. It has for-its object the elimination of sulfur, arsenic, tellurium and other deleterious matter, and render the ore suitable for'successful subsequent treatment by amalgamation, cyanidation or other methods of separating the values from the ore.

My invention therefore consists in the process of treating ores which will be fully disclosed in the following. specification andclaim.

It is my purpose to exclude atmospheric air and treat the ore in an airtightfurnace, into which the ore and a combination of dry chemicals are placed, and subject it to ex-' .20 terior and interior heat; the exterior hea't beingfrom wood or coal fires, oil, as, or

electric heat, and the interior heat y ad-- mitting highly heated hydrogen gas through a feed pipe by pressure; wit in the furnace I have a number of revolving lifting plates or shelves which agitate the ore and keep it moving.

The combination of chemicals used in my process consists oflime, usually air-slacked, powdered sal ammoniac and. common table salt.

The quantity of each upon the character of the ore, and it is some.-

Application filed Angfist 13, 1920. Serial No. 128,990.

of sodium hfydroxide, charcoal,

or the purpose of asslstmg in recious metals. 1

chemical depends" times necessary to add a small roportion one dust or litharge, separating and cleansing the The object of the chemica s is to prevent escape of the precious metals in the fumes, to separate the precious metalsfrom all baser metals; and to'cleanse them from all im-'* purities and acids; no moisture being admitted at any time during operations. The ore being desulfurized and thoroughly released from all baser metals and minerals TO Evans can annuaby the aforesaid treatment, when cooled, is

in condition for recovering the precious metals therein contained, by amalgamation means.

or other approved experi It has been found, from practical ments, that my process produces better results than any known rocess heretofore used.

Other dry chemica s may be used, but they are all superfluous. 1 Having thus described myprocess, what I claim is:

The process of treatin ores containing precious meta s, which consists in mixing ore with lime, salt and sal-am: moniac, heating themixture in an atmosphere othydrogen while being a 'tated, and separating 'out the precious meta v In testimony whereof I hereby aflix my signature.

Gnome W. a EVANS. 

